package com.woshengqile.shiro;

/**
 * Created by wangrenhui on 14-1-3.
 */
/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

import java.io.IOException;
import java.util.Arrays;

import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.apache.shiro.SecurityUtils;
import org.apache.shiro.authc.AuthenticationException;
import org.apache.shiro.authc.AuthenticationToken;
import org.apache.shiro.authc.UsernamePasswordToken;
import org.apache.shiro.authz.UnauthenticatedException;
import org.apache.shiro.session.Session;
import org.apache.shiro.session.UnknownSessionException;
import org.apache.shiro.subject.Subject;
import org.apache.shiro.web.util.WebUtils;

import com.woshengqile.shiro.exception.IncorrectCaptchaException;
import com.woshengqile.util.EncriptionKit;


/**
 * An <code>AuthenticationFilter</code> that is capable of automatically
 * performing an authentication attempt based on the incoming request.
 *
 * @since 0.9
 */
public abstract class ShiroAuthenticatingFilter extends
		ShiroAuthenticationFilter {
	public static final String PERMISSIVE = "permissive";
	public static final String DEFAULT_CAPTCHA_PARAM = "captcha";
	public static boolean useCaptcha = true;

	// TODO - complete JavaDoc

	protected boolean executeLogin(ServletRequest request, ServletResponse response) throws Exception {
		UsernamePasswordToken token = createToken(request, response);
		if (token == null) {
			String msg = "createToken method implementation returned null. A valid non-null AuthenticationToken "
					+ "must be created in order to execute a login attempt.";
			throw new IllegalStateException(msg);
		}
		try {
			if (useCaptcha)
				doCaptchaValidate((CaptchaUsernamePasswordToken) token);
			Subject subject = getSubject(request, response);
			subject.login(token);
			return onLoginSuccess(token, subject, request, response);
		} catch (AuthenticationException e) {
			return onLoginFailure(token, e, request, response);
		}
	}

	protected abstract UsernamePasswordToken createToken(ServletRequest request, ServletResponse response) throws Exception;

	protected UsernamePasswordToken createToken(String username, String password, ServletRequest request, ServletResponse response) {
		boolean rememberMe = isRememberMe(request);
		String host = getHost(request);
		return createToken(username, password, rememberMe, host);
	}

	protected UsernamePasswordToken createToken(String username, String password, boolean rememberMe, String host) {
		return new UsernamePasswordToken(username, password, rememberMe, host);
	}

	// 创建 Token
	protected UsernamePasswordToken createToken(String username, String password, String captcha, ServletRequest request, ServletResponse response) {
		boolean rememberMe = isRememberMe(request);
		String host = getHost(request);
		return new CaptchaUsernamePasswordToken(username, password, rememberMe, host, captcha);
	}

	protected boolean onLoginSuccess(AuthenticationToken token, Subject subject, ServletRequest request, ServletResponse response) throws Exception {
		return true;
	}

	protected boolean onLoginFailure(AuthenticationToken token, AuthenticationException e, ServletRequest request, ServletResponse response) throws Exception {
		return false;
	}

	/**
	 * Returns the host name or IP associated with the current subject. This
	 * method is primarily provided for use during construction of an
	 * <code>AuthenticationToken</code>.
	 * <p>
	 * The default implementation merely returns
	 * {@link javax.servlet.ServletRequest#getRemoteHost()}.
	 *
	 * @param request
	 *            the incoming ServletRequest
	 * @return the <code>InetAddress</code> to associate with the login attempt.
	 */
	protected String getHost(ServletRequest request) {
		return request.getRemoteHost();
	}

	/**
	 * Returns <code>true</code> if &quot;rememberMe&quot; should be enabled for
	 * the login attempt associated with the current <code>request</code>,
	 * <code>false</code> otherwise.
	 * <p>
	 * This implementation always returns <code>false</code> and is provided as
	 * a template hook to subclasses that support <code>rememberMe</code> logins
	 * and wish to determine <code>rememberMe</code> in a custom mannner based
	 * on the current <code>request</code>.
	 *
	 * @param request
	 *            the incoming ServletRequest
	 * @return <code>true</code> if &quot;rememberMe&quot; should be enabled for
	 *         the login attempt associated with the current
	 *         <code>request</code>, <code>false</code> otherwise.
	 */
	protected boolean isRememberMe(ServletRequest request) {
		return false;
	}

	/**
	 * Determines whether the current subject should be allowed to make the
	 * current request.
	 * <p>
	 * The default implementation returns <code>true</code> if the user is
	 * authenticated. Will also return <code>true</code> if the
	 * {@link #isLoginRequest} returns false and the &quot;permissive&quot; flag
	 * is set.
	 *
	 * @return <code>true</code> if request should be allowed access
	 */
	@Override
	protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) {
		return super.isAccessAllowed(request, response, mappedValue) || (!isLoginRequest(request, response) && isPermissive(mappedValue));
	}

	/**
	 * Returns <code>true</code> if the mappedValue contains the
	 * {@link #PERMISSIVE} qualifier.
	 *
	 * @param mappedValue
	 *            mappedValue
	 * @return <code>true</code> if this filter should be permissive
	 */
	protected boolean isPermissive(Object mappedValue) {
		if (mappedValue != null) {
			String[] values = (String[]) mappedValue;
			return Arrays.binarySearch(values, PERMISSIVE) >= 0;
		}
		return false;
	}

	/**
	 * Overrides the default behavior to call {@link #onAccessDenied} and
	 * swallow the exception if the exception is
	 * {@link org.apache.shiro.authz.UnauthenticatedException}.
	 */
	@Override
	protected void cleanup(ServletRequest request, ServletResponse response, Exception existing) throws ServletException, IOException {
		if (existing instanceof UnauthenticatedException || (existing instanceof ServletException && existing.getCause() instanceof UnauthenticatedException)) {
			try {
				onAccessDenied(request, response);
				existing = null;
			} catch (Exception e) {
				existing = e;
			}
		}
		super.cleanup(request, response, existing);

	}

	protected String getCaptcha(ServletRequest request) {
		return WebUtils.getCleanParam(request, DEFAULT_CAPTCHA_PARAM);
	}

	// 验证码校验
	protected void doCaptchaValidate(CaptchaUsernamePasswordToken token) {
		Session session = SecurityUtils.getSubject().getSession();
		if (session == null) {
			throw new UnknownSessionException("Unable found required Session");
		} else {
			if (session.getAttribute(DEFAULT_CAPTCHA_PARAM) != null) {
				String captcha = session.getAttribute(DEFAULT_CAPTCHA_PARAM).toString();
				// String captcha = CookieUtils.getCookie(request, AppConstants.CAPTCHA_NAME);
				if (token.getCaptcha() != null && captcha.equalsIgnoreCase(EncriptionKit.encrypt(token.getCaptcha().toLowerCase()))) {
					return;
				}
			}
			throw new IncorrectCaptchaException();
		}
	}
}